Many manufacturing processes require the use of pure inert gases such as the rare or noble gases, helium, neon, argon, krypton, xenon or nitrogen. One particular example of their use is in the manufacture of semiconductor devices. Before use impure inert gases must be purified by removing contaminant gases such as CO, CO.sub.2, CH.sub.4, O.sub.2 and H.sub.2. GB Patent Application Publication Nos. 2,177,079 A and 2,177,080 A describe methods for the purification of inert gases to remove these impurity gases. However these two GB Patent Application Publications give no information relative to the problems of the maintenance of extremely low levels of hydrogen.
Although there is no quantitative measure available which relates the percentage of defects found during the manufacture of semiconductor devices with the partial pressure of hydrogen present during the manufacturing process, it is generally believed that the lower the hydrogen partial pressure, the lower the number of defects found.